Spaces within spaces: rat parietal cortex neurons register position across three reference frames.

We recorded parietal cortex neurons as rats traversed squared spiral tracks. Spatial firing patterns distinguished the behaviorally identical track segments composing loops, yet recurred with increasing or decreasing amplitude across the five loops composing the full track. These results indicate that parietal cortex neurons simultaneously respond to spatial relationships in multiple external reference frames, a phenomenon that may reflect a neural mechanism for relating parts to a whole.